Are the nylon pins durable?

Our screen doors are very old, over 30 years but are in excellent condition aside from the springs needing to be replaced. I cannot find any matches locally nor can I find any information on the doors that says who manufactured them. We have open barrel hinges. One side of the hinge attaches to the door jamb with 3 screws. The only way to secure the door to the hinge is to use the springs with the pins. The pins go in holes on either side of the opening in the door and secure it to the door frame. There are 4 hinges total per door. Right now, the pins are metal and since this is what's holding up the weight of the door and holding it onto the hinges, I am just curious if the 40-165 pins will be durable. Thank you! The door weighs over 50lbs--quite heavy. Also, we have 3 good hinges but one that needs repair--is there anyone that can help get a replacement?